1. Field of the Invention
The present invention relates to a character string recognition apparatus in a character recognition apparatus associated with a character recognition apparatus OCR and software OCR which have recently been more and more demanded as document input appliances.
2. Description of the Related Art
As a method of recognizing a word by dividing a handwritten character string into partial character strings, there has been a suggestion for recognizing a word in an area enclosed by the characters (key characters) detected as delimiters such as  (capital), , , and  (prefecture),  (city),  (ward),  (county), etc. in a handwritten address (for example, Japanese Patent Publication No. 11-161740, Japanese Patent Publication No. 11-328315).
However, the above mentioned method is used for a handwritten address, and no method has been developed for a common handwritten character string other than an address. In an address, each key character can be a delimiter of character strings, and no plural characters have been used as key characters, that is, a key word.
In the conventional key character extraction system for use in recognizing a handwritten address, a key character is limited to { (capital),  (prefecture),  (prefecture),  (prefecture),  (city),  (ward),  (county),  (town),  (village)}. However, when a target character string is not an address, it is necessary to newly set a key character each time a character string recognizing process is performed.
Furthermore, since the number of key characters is one (1) to be extracted from a character string in the conventional method, a key word containing two or more characters cannot be successfully extracted due to, for example, touching characters in the key word, if the conventional method is applied as is.
Additionally since a high precision rejecting process has been not performed in the conventional word recognizing method, a word can be misrecognized as a completely wrong word, thereby discouraging users.